Effect of the natural progesterone and estradiol on the fertility of cows (bos taurus/bos indicus) inseminated in time fixed in the tropics of Guerrero, Mexico

Livestock in Mexico is one of the most profitable productive activities, currently has 30, 833, 978 heads of cattle. Achieving a calf per cow per year in a bovine production system means that, after 365 days of the year, 283 days of the gestation period, the females should be pregnant again after 82 days of calving. Taking into account the 40 to 60 days of recovery of reproductive capacity after childbirth, cows have only one estrus or two to achieve the next pregnancy. The timely detection of jealousy is one of the main factors for good reproductive performance in livestock, considering the failure of this activity, one of the main reasons for the increase in the interval between births in herds. In order to avoid the problem with heat detection, various estrus synchronization protocols have been developed. These treatments are known as fixed-time artificial insemination protocols (IATF).1 There are protocols for the synchronization of estrus that can induce the presence of heats in 75-90% of the animals in a period of 5 days. Without the use of estrus synchronization, only 30% of estrus detection in animals can be achieved. With the synchronization, a conception range of 65% is reached, the difference lies in the gestation range, where with synchronization a pregnancy percentage of 49% is reached and only 21% without using this protocol.2 In this context, the importance of the work is to provide an accessible, reliable and updated source of information about the different techniques of estrus synchronization on the rate of gestation of cows.